Which of the following terms describes lying on the back?

The term that describes lying on the back is "supine." In medical terminology, supine refers specifically to a position where a person is lying flat on their back, facing upwards. This position is commonly used in various medical settings, such as during examinations, surgeries, or while administering treatment, because it allows for easy access to the chest and other body areas.

In contrast, the term "prone" describes the position where a person is lying on their stomach. The recovery position typically refers to a side-lying posture used for unconscious but breathing patients to help keep their airway clear. "Proximal" is an anatomical term that refers to a position closer to the center of the body or the point of attachment, rather than a lying position. Therefore, when identifying the position of lying on the back, "supine" is the accurate term.